Abstract
AbstractA detailed knowledge of the crustal thickness in the northeastern North China Craton (NCC) is important for understanding the unusual Phanerozoic destruction of the craton. We achieve this goal by employing a 2‐D wave equation‐based migration method to P receiver functions from 198 broadband seismic stations, using Ps conversions and surface‐reflected multiples. By combining receiver function images along 19 profiles, we constructed a high‐resolution Moho depth model for the northeastern NCC. The results present dominant E‐W Moho depth variations similar to previous observations and new regional N‐S variations beneath both sides of the North‐South Gravity Lineament. To the west, while a deeper Moho (∼42 km) appears in the interior of the Trans‐North China Orogen, a relatively shallow Moho (∼38 km) exists in the northern margin of the Trans‐North China Orogen to western NCC. To the east, the crust beneath the Yan Mountains in the marginal area is thicker (∼32–40 km) than that (∼26–32 km) beneath the Bohai Bay Basin in the craton interior, and the Moho further shallows from NE (∼32 km) to SW (∼26 km) within the basin. Along with other observations, we conclude that the dominant E‐W difference may have been associated with the Paleo‐Pacific plate subduction under eastern Asia since the Mesozoic. The newly observed complex N‐S variations may have reflected the structural heterogeneity of the cratonic lithosphere inherited since the formation of the NCC in the Paleoproterozoic, or spatially uneven effects on the cratonic lithosphere of subsequent thermotectonic events during the long‐term evolution of the craton, or both.
Highlights
Ubiquitous structural heterogeneities in the continental lithosphere are believed to have played essential roles in the tectonic evolution and dynamics of continents, in the stabilization/reactivation of cratons (e.g., Begg et al, 2009; Chen, 2010; Chen et al, 2014)
We suggest that the intense crust-mantle interactions are absent in the interior of the TNCO or that the crust may have retained its Archean nature and still be relatively stable, with only slight thinning resulted from tectonic extension in the region
Given the spatiotemporal concordance between the Cenozoic lithospheric modification with the tectonic processes induced by the India-Eurasia collision, we propose that the Cenozoic lithospheric modifications at the boundaries of the Ordos Block may have initiated in the northern marginal areas and may be predominantly influenced by the India-Eurasia collision, less intensive and much later than the Mesozoic lithospheric reactivation and destruction in the eastern North China Craton (NCC)
Summary
Ubiquitous structural heterogeneities in the continental lithosphere are believed to have played essential roles in the tectonic evolution and dynamics of continents, in the stabilization/reactivation of cratons (e.g., Begg et al, 2009; Chen, 2010; Chen et al, 2014). Several mechanisms have been proposed to be responsible for the destruction of the eastern NCC, including the Paleo-Pacific plate subduction (Griffin et al, 1998; Sun et al, 2007), the North-South China collision (Yin & Nie, 1993; Zhang, 1997), the collision of an amalgamated North China-Mongolian plate with the Siberian plate (Davis et al, 2001), the India-Eurasia collision (Menzies et al, 1993), and an enhanced mantle temperature associated with plumes (Deng et al, 2004) Even with these prior studies, how the various tectonic events influenced the major tectonic units and boundary zones of the NCC is still not fully understood. We investigated the correlations of the Moho depth with surface geology, gravity anomalies, and lithospheric thickness in detail, and we discuss their tectonic implications on the Phanerozoic destruction of the NCC
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